High Park Fire ratchets up water treatment costs

Nov. 23, 2012

Lisa Voytko, water production manager of Water Treatment Facility, stands in Gateway Park's pre-sedimentation basin.

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If you stand on the Poudre River’s shore just above Gateway Natural Area in Poudre Canyon, the challenge the city faces in treating its drinking water after the High Park and Hewlett fires is something you can put your feet on.

After the summer’s fires incinerated large swathes of the Poudre River watershed, tons of ash and debris washed into the river during rainstorms, wreaking havoc with one of Fort Collins’ main sources of drinking water.

Standing on a layer of ash caked on the pebbly shore of the Poudre River, Lisa Voytko, city water production manager, said the High Park Fire could cost Fort Collins Utilities $1 million a year for the next two years just to keep the additional sediment out of the city’s tap water.

The city has a major water diversion operation in Poudre Canyon, the source of about half of the city’s water in most years.

At the Fort Collins-Loveland, North Weld County and East Larimer County water districts’ water intake and diversion dam a few miles upstream of Gateway Natural Area, it’s not hard to understand why the fire might cost the city so much.

A massive layer of ash and debris several feet thick has accumulated behind the dam since the fire. Once it reaches the river, the sediment becomes suspended in the water and ends up in the city’s water intake at Gateway Natural Area.

“It’s a big deal because we have to remove the sediment for all our processes to work properly, and it creates a lot of additional residuals or sludge that we have to take care of and also any chemicals we have to add to take out all the solids from the system,” Voytko said.

All that dirt, silt, ash and sand ends up in the city’s “presedimentation basin” — the round, domed building on the left side of the Gateway Natural Area entrance roadway.

That’s where the city has to spend the money to keep the debris from mucking up its water treatment system.

The basin “has the capacity to settle out large particles, sand, sediment and other material before it gets into the pipeline that goes to the water treatment facility,” Voytko said. “This is the facility that we had to clean out several occasions this summer as a result of sediment buildup.”

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Normally, cleaning out the basin is an annual event. But after the fires this year, the city cleaned out the basin four times in September.

Smaller bits of silt and debris remaining in the water as it’s piped to the city’s water treatment plant at the west end of Laporte Avenue are removed later in the purification process.

Keeping the system clean is only one cost the city is expected to incur to ensure adequate water supplies in the coming year.

It’s unknown both how much water will be flowing down the Poudre next spring and, as the drought continues, how much water the city will be allowed to take from the Colorado-Big Thompson Project, or C-BT, and Horsetooth Reservoir, Fort Collins water resources engineer Donnie Dustin told City Council on Tuesday.

The city, he said, is looking for ways to increase the amount of C-BT water it has access to, and that means the city may decide not to rent water to farmers, reducing Fort Collins Utilities’ revenue by $700,000 in 2013.

“Restrictions are likely to be implemented early in the spring as a precaution,” he said, adding that farmers that rely on Fort Collins for water are going to hurt next year.